PyBullet / BulletRobotics:

Implement collisionFilterPlugin, use setCollisionFilterPair to enable or disable collision detection between specific pairs of objects.
Also, expose setCollisionFilterGroupMask as PyBullet API and in urdf using the tag <collision group="1" mask="2"/>.
See examples/pybullet/examples/collisionFilter.py for an example.
PyBullet default: Lower the warmstarting factor, for maximal coordinates rigid bodies for more stable simulation.
Add btCollisionWorld::refreshBroadphaseProxy to easier recreate the broadphase proxy without adding/removing objects to the world.

examples/SharedMemory/plugins/b3PluginCollisionInterface.h

@@ -0,0 +1,33 @@
+#ifndef B3_PLUGIN_COLLISION_INTERFACE_H
+#define B3_PLUGIN_COLLISION_INTERFACE_H
+
+enum b3PluginCollisionFilterModes
+{
+	B3_FILTER_GROUPAMASKB_AND_GROUPBMASKA=0,
+	B3_FILTER_GROUPAMASKB_OR_GROUPBMASKA
+};
+
+struct b3PluginCollisionInterface
+{
+	virtual void setBroadphaseCollisionFilter(
+		int objectUniqueIdA, int objectUniqueIdB,
+		int linkIndexA, int linkIndexB, 
+		bool enableCollision)=0;
+
+	virtual void removeBroadphaseCollisionFilter(
+		int objectUniqueIdA, int objectUniqueIdB,
+		int linkIndexA, int linkIndexB)=0;
+
+	virtual int getNumRules() const = 0;
+
+	virtual void resetAll()=0;
+
+	virtual int needsBroadphaseCollision(int objectUniqueIdA, int linkIndexA, 
+		int collisionFilterGroupA,int collisionFilterMaskA,  
+		int objectUniqueIdB, int linkIndexB,
+		int collisionFilterGroupB,int collisionFilterMaskB, 
+		int filterMode
+		)=0;
+};
+
+#endif //B3_PLUGIN_COLLISION_INTERFACE_H